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961.
氮离子束注入与紫外线辐射对姬松茸担孢子萌发的影响显著不同,表现出一定程度的马鞍型效应.不同剂量的氮离子束注入姬松茸担孢子,其产生的生物学效应不同:氮离子注入束流为200×2.6×1013N /cm2,筛选到一株箱栽生物学效率提高47.0%的姬松茸新菌株AbML11;氮离子注入束流为400×2.6×1013N /cm2,筛选到一株子实体呈现白色突变的姬松茸新菌株AbML7;氮离子注入束流为500×2.6×10"N13/cm2,筛选到一株具有AEC抗性突变的姬松茸新菌株AbML2. 相似文献
962.
963.
Rapid recovery, immobilization, and silica encapsulation of a dual-fusion enzyme was achieved by using iminodiacetic acid (IDA) modified magnetic nanoparticle as a carrier. D-amino acid oxidase (DAAO) of Rhodosporidium toruloides was used as a model enzyme in which a silica-precipitating peptide R5 and a metal ion complexing peptide (His)(6) were fused to its N- and C-terminal, respectively. After charging the magnetic particle with Cu(2+), the dual-fusion DAAO of 0.43 g could be directly recovered from the recombinant E. coli crude extract and immobilized on 1 g of the magnetic particle. Once in contact with hydrolyzed tetramethoxysilane (TMOS), the homogeneously dispersed immobilized dual-fusion DAAO was biosilicificated to form aggregates with size about 50 microm. The silica-encapsulated immobilized DAAO demonstrated a pyruvic acid production rate comparable with that of the naked immobilized DAAO in five repeated batch reactions when D-alanine was used as substrate. Furthermore, 85% of its activity remained after incubation at 60 degrees C for 1 h while the naked immobilized DAAO lost all its activity. This process provides the advantages that recombinant fusion enzyme can be directly recovered from crude extract, silica encapsulation protects the enzyme from leakage and denaturation, and the enzyme activity can be easily retrieved by applying a magnetic field. 相似文献
964.
The previously reported class of potent inorganic inhibitors of Na,K-ATPase, named MCS factors, was shown to inhibit not only
Na,K-ATPase but several P-type ATPases with high potency in the sub-micromolar range. These MCS factors were found to bind
to the intracellular side of the Na, K-ATPase. The inhibition is not competitive with ouabain binding, thus excluding its
role as cardiac-steroid-like inhibitor of the Na,K-ATPase. The mechanism of inhibition of Na,K-ATPase was investigated with
the fluorescent styryl dye RH421, a dye known to report changes of local electric fields in the membrane dielectric. MCS factors
interact with the Na,K-ATPase in the E1 conformation of the ion pump and induce a conformational rearrangement that causes a change of the equilibrium dissociation
constant for one of the first two intracellular cation binding sites. The MCS-inhibited state was found to have bound one
cation (H+, Na+ or K+) in one of the two unspecific binding sites, and at high Na+ concentrations another Na+ ion was bound to the highly Na+-selective ion-binding site. 相似文献
965.
Wet mass and water content of four lots of whole eggs did not change throughout embryonic development of rainbow trout Oncorhynchus mykiss. Eggs in all four lots accumulated Na+ . Eggs in lots 2 and 4 also accumulated Ca2+ and Cl- , whereas eggs in lot 1 showed no significant change in Ca2+ or Cl- and eggs in lot 3 showed no change in Cl- and a small loss of Ca2+ . Although the Na+ content of embryonic tissues increases in the later stages of development, the yolk sac content remained constant, indicating uptake of Na+ from the environment. Na+ uptake by whole eggs was non-saturable, consistent with diffusion of Na+ across the chorion into the perivitelline fluid. Na+ uptake in dechorionated embryos was saturable, as was Ca2+ uptake by both whole eggs and dechorionated embryos, consistent with active uptake or facilitated diffusion mechanisms at the surface of embryos. Very low Ca2+ uptake rates in dechorionated embryos suggest that the Ca2+ uptake mechanism is not fully developed until after hatching. 相似文献
966.
Na+/K+-ATPase plays a key role in the transport of Na+ throughout the nephron, but ageing appears to be accompanied by changes in the regulation and localization of the pump. In
the present study, we examined the effect of in vitro cell ageing on the transport of Na+ and K+ ions in opossum kidney (OK) cells in culture. Cells were aged by repeated passing, and Na+/K+-ATPase activity and K+ conductance were evaluated using electrophysiological methods. Na+K+-ATPase α1– and β1-subunit expression was quantified by Western blot techniques. Na+/H+ exchanger activity, changes in membrane potential, cell viability, hydrogen peroxide production and cellular proliferation
were determined using fluorimetric assays. In vitro cell ageing is accompanied by an increase in transepithelial Na+ transport, which results from an increase in the number of Na+/K+-ATPase α1- and β1-subunits, in the membrane. Increases in Na+/K+-ATPase activity were accompanied by increases in K+ conductance as a result of functional coupling between Na+/K+-ATPase and basolateral K+ channels. Cell depolarization induced by both KCl and ouabain was more pronounced in aged cells. No changes in Na+/H+ exchanger activity were observed. H2O2 production was increased in aged cells, but exposure for 5 days to 1 and 10 μM of H2O2 had no effect on Na+/K+-ATPase expression. Ouabain (100 nM) increased α1-subunit, but not β1-subunit, Na+/K+-ATPase expression in aged cells only. These cells constitute an interesting model for the study of renal epithelial cell
ageing. 相似文献
967.
Javier Arias 《Inorganica chimica acta》2011,365(1):501-504
The crown ether isocyanide CNR (R = benzo-15-crown-5) reacts with silver(I) salts in the appropriate molar ratio to give [Ag(CNR)n]X (n = 1, 2; X = CF3SO3, BF4). X-ray diffraction studies of [Ag(CF3SO3)(CNR)] show the molecules associated in a dinuclear manner with an antiparallel orientation. The silver centers are tetracoordinated to the isocyanide and to three oxygens, one from the triflate anion and two from the second crown ether in the dimer. The molecular structure displays five cycles: the two 15-crown ether rings, two five-membered argentacycles and a 22-membered diargentacycle. The crown ether in these complexes is able to detect alkaline cations from M(CF3SO3) (M = Li, Na, K) by NMR in d6-acetone solutions, and to distinguish Li+-Na+ from K+. 相似文献
968.
Qing Zhang Christophe Didier Wei Kong Pang Yajie Liu Zhijie Wang Sean Li Vanessa K. Peterson Jianfeng Mao Zaiping Guo 《Liver Transplantation》2019,9(30)
Potassium‐ion batteries (PIBs) are an emerging, affordable, and environmentally friendly alternative to lithium‐ion batteries, with their further development driven by the need for suitably performing electrode materials capable of reversibly accommodating the relatively large K+. Layer‐structured manganese oxides are attractive as electrodes for PIBs, but suffer from structural instability and sluggish kinetics of K+ insertion/extraction, leading to poor rate capability. Herein, cobalt is successfully introduced at the manganese site in the KxMnO2 layered oxide electrode material and it is shown that with only 5% Co, the reversible capacity increases by 30% at 22 mA g‐1 and by 92% at 440 mA g‐1. In operando synchrotron X‐ray diffraction reveals that Co suppresses Jahn–Teller distortion, leading to more isotropic migration pathways for K+ in the interlayer, thus enhancing the ionic diffusion and consequently, rate capability. The detailed analysis reveals that additional phase transitions and larger volume change occur in the Co‐doped material as a result of layer gliding, with these associated with faster capacity decay, despite the overall capacity remaining higher than the pristine material, even after 500 cycles. These results assert the importance of understanding the detailed structural evolution that underpins performance that will inform the strategic design of electrode materials for high‐performance PIBs. 相似文献
969.
In this study, we investigated the effects of arachidonic acid, a PLA2-produced lipid metabolite, on the lysosomal permeability, osmotic sensitivity and stability. Through the measurements of lysosomal β-hexosaminidase free activity, membrane potential, intralysosomal pH, and lysosomal latency loss in hypotonic sucrose medium, we established that arachidonic acid could increase the lysosomal permeability to both potassium ions and protons, and enhance the lysosomal osmotic sensitivity. As a result, the fatty-acid-promoted entry of potassium ions into the lysosomes via K+/H+ exchange, which could produce osmotic imbalance across their membranes and osmotically destabilize the lysosomes. In addition, the enhancement of lysosomal osmotic sensitivity caused the lysosomes to become more liable to destabilization in osmotic shock. The results suggest that arachidonic acid may play a role in the lysosomal destabilization. 相似文献
970.
The lateral leaflets of Desmodium motorium exhibit rhythmic upward and downward movements with a period in the minute range. Apoplasmic K+ and H+ activities were monitored in situ in the abaxial part of the pulvini with ion-selective microelectrodes. An extracellular electric potential was recorded simultaneously. The apoplasmic H+ activity of all pulvini exhibiting a regular rhythm of the extracellular electric potential oscillated with the same period between about 10 and 20 mM. The apoplasmic K+ activity was high when the membrane potential of the motor cells was depolarized (about 36 mV) and the cells were shrunken. In contrast, the apoplasmic K+ activity was low in the swollen state of the motor cells, when the membrane potential was hyperpolarized (about -136 mV). The volatile anesthetic enflurane suppressed reversibly the movement of the leaflets. The same treatment also arrested spontaneous oscillations in the apoplasmic K+ activity in the pulvinus. The apoplasmic K+ activity oscillated roughly in phase with the K+ activity between pH 6.6 and 6.0. Application of white light disturbed the rhythm and increased the extracellular pH. Our results indicate that the physiological mechanism that drives the lateral leaflet movements of Desmodium motorium is closely related to the osmotic motors mediating the leaf movements of Mimosa, Samanea and Phaseolus.Abbreviations Em
membrane potential
- Eex
extracellular electric potential
- Hex
extracellular H+ activity
- Kex
extracellular K+ activity
- Rex
extracellular electrical resistance
B. Antkowiak was supported by the Stiftung Volkswagenwerk. 相似文献